1. Field of the Invention
The present invention relates to lamp sockets for an automobile headlight or the like.
2. Description of the Related Art
Recently, discharge lamps, which are brighter, lower in power consumption, and longer in useful life than halogen lamps, are widely used for automobile headlight in consideration for safety. It is necessary to apply a high voltage above 13 kV to the discharge lamp for automobile headlight at the starting time. The starter circuit for applying the high voltage at the starting time and the lamp socket into which a lamp is mounted are made separately, resulting in the large number of components and large space occupied by the components.
Japanese patent application Kokai No. 10-214733 proposed that the starter circuit is housed in the socket body of a lamp socket to reduce the number of components and the space.
It comprises a coil bobbin around which a secondary coil is wound, a core placed in the bobbin, a coil case for housing the bobbin, a primary coil wound around the coil case to form a high-voltage transformer, an ignition circuit for a discharge lamp mounted on a printed circuit board, a housing for receiving the printed circuit board and a lamp socket, and a dielectric resin filled in the housing to form a discharge lamp unit.
However, the above discharge lamp unit is made by putting the high-voltage transformer and the print circuit board in the housing and filling the housing with a resin to provide the unit so that the number of assembling steps is too large to do it readily.
Japanese patent application Kokai No. 10-223005 proposed that the starter circuit is housed in the socket body of a lamp socket.
It comprises a body case having a socket section provided on a side of the transformer receiving section for connection with a discharge lamp. An ignition transformer, which is housed in the transformer receiving section, has a secondary coil for connection with the central high-voltage output terminal of the socket section. The primary coil is connected to the low-voltage output terminal provided on the side of the socket section via a circuit section.
However, this lamp socket has no separation member between the high-voltage and low-voltage output terminals and fails to meet the required high break-down voltage, producing a spark between the terminals and a leak of the high-voltage.
Accordingly, it is an object of the invention to provide a lamp socket that needs neither resin filling nor large number of assembling steps while keeping the electronics components incorporated.
It is another object of the invention to provide a lamp socket that is able to provide a high break-down voltage and eliminate a spark between the terminals and a leak of the high-voltage.
According to an aspect of the invention there is provided a lamp socket comprising a socket body with a socket cavity into which a plugging section of a lamp is plugged; a central terminal provided at a center of said socket cavity for contact with a lamp terminal of said lamp; a side terminal provided in a side wall of said socket cavity for contact with a contact section of said plugging section; a unit receiving section provided in said socket body at a position opposite to said socket cavity; said socket body, said central terminal, said side terminal, and said unit receiving section constituting a lamp socket unit; an inside unit including a circuit section for starting said lamp and high-voltage and low-voltage output terminals connected to said circuit section; said inside unit being housed in said unit receiving section such that said high-voltage and low-voltage output terminals are brought into contact with said central and side terminals, respectively.
By housing the inside unit in the unit receiving section and bringing the high-voltage and low-voltage output terminals into contact with the central and side terminals, respectively, it is possible to assemble the lamp socket in a small number of assembling steps while keeping the electronics components incorporated.
The lamp socket according to the invention may further comprise a connector section for connecting said circuit section to a power source. The connector section facilitates a supply of electrical power to the inside unit. The lamp socket according to the invention may further comprise a cover for covering said inside unit in said unit receiving section. The inside unit may comprise a board of a conductive plate; a unit body including said board; a plurality of electronics components mounted on said board to form said circuit section. This configuration makes it easier to assemble the lamp starter circuit and the electronics components unit.
According to another aspect of the invention there is provided a lamp socket comprising a socket body with a socket cavity into which a plugging section of a lamp is plugged; a central terminal provided at a center of said socket cavity for contact with a lamp terminal of said lamp; a side terminal provided in a side wall of said socket cavity for contact with a contact section of said plugging section; a unit receiving section provided in said socket body at a position opposite to said socket cavity; said socket body, said central terminal, said side terminal, and said unit receiving section constituting a lamp socket unit; an inside unit including a circuit section for starting said lamp and high-voltage and low-voltage output terminals connected to said circuit section; said unit receiving section being divided into first and second storage rooms such that said first and second storage rooms receive said central and side terminals, respectively; a seal abutment section provided in either said first storage room or said inside unit so as to surround said central terminal; a seal mounting section provided in said second storage room so as to surround said high-voltage output terminal; a dielectric seal member provided in the seal mounting section; said inside unit being housing in said unit receiving section so that not only said high-voltage and low-voltage terminals are brought into contact with said central and side terminals, respectively, but also said dielectric seal member into abutment with said seal abutment section.
The lamp socket may further comprises a separation wall in said unit receiving section so as to separate said first and second storage rooms or a connection terminal for connecting said low-voltage output terminal with said side terminal to bring said low-voltage output terminal to said side terminal. The lamp socket is assembled by placing the inside unit in the unit receiving section such that the high-voltage and low-voltage output terminals are brought into contact with the central and side terminals to assemble the lamp socket. The dielectric seal member separates the high-voltage and low-voltage output terminals to provide a high break-down voltage and prevent a spark between them and a leak of the high-voltage.